In recent years, it has become increasingly important to protect the health of care providers without compromising that of the patient. This reflects the increasing incidence of such infectious diseases as tuberculosis, acquired immune deficiency syndrome, and herpes. Many factors should be considered in selecting a proper protection device. For example, verbal, as well as visual communication between a care provider and a worried patient can be critical in reassuring and displaying concern to the patient. Furthermore, in an emergency situation, a protective system that is easy to don and does not need facial or cranial adjustment saves time. In addition, a protective device should be comfortable to wear for long periods of time.
Generally, while masking and shielding protective systems, including masks and respirators, known prior to the present invention provide a high level of protection, they are difficult to put on and properly adjust. Furthermore, these devices may be uncomfortable to wear, even for short periods of time. Additionally, many conceal part or all of the wearers'face, particularly the mouth.
Protective systems incorporating ventilation or ventilation systems are known. U.S. Pat. No. 4,055,172 (Knab) discloses the use of a vacuum system to draw air into and through the protective helmet and gown of the surgeon and to filter that air prior to returning it to the room. The lack of mobility created by the need to tether the user to the device is not desirable, and there is no mention of the need to protect the user from contaminants in the room. The issue of mobility is addressed by U.S. Pat. No. 4,019,508 (Der Estephaniuan, et al.). It describes a "back pack" self-contained device to be worn by surgeons. However, wearing a back pack may create balance, awkwardness and fatigue problems for the user and, again, there is no mention of protecting the user from contaminants in the ambient air.
Positive pressure respirators are broadly used in industrial applications. Their use is frequently regulated by government agencies. These devices provide filtered air to a user. A compressed air line or a blower is used to deliver the air to the hard-hat helmet or face piece of the respirator. U.S. Pat. No. 4,462,399 (Braun) discloses a "filter in helmet" concept, wherein a face sealing means is used to seal the device against the face. As disclosed in U.S. Pat. No. 4,280,491 (Berg et al.), air exit openings may be provided to allow air to flow out of the device. Such devices are also described in a 3M brochure entitled "Positive Pressure Respirators" (3M, St. Paul, Minn.). The intent of such devices is to protect the wearer from the environment, and no provision is made to remove wearer originated contamination from the positive pressure system before the air exits to the environment.
Protection of the face including the eyes, nose, ears and mouth is taught in U.S. Pat. No. 4,965,887 (Paoluccio et al.). This device uses a generally cylindrical clear plastic face shield held in position by associated eye glasses. The patent also suggests the attachment of the shield to a hard hat or to other forms of head gear. The use of an extended skirt attached to the bottom of the shield is suggested for further protection of the wearer. Openings on the top and bottom of a fluid impermeable skull cap are provided for relief from the heat built up from wearing the device. No respiratory protection is provided to the wearer.
Protective masking and shielding systems for protecting and covering the head and/or face of the wearer have employed an adjustable harness to secure a hard-hat and/or face-shield protective device to the head of the wearer. These harnesses combine a horizontal head band encircling the head with a head band that extends from side to side over the crown of the head. The protective devices are suspended from or mounted on the harness. Typical harnesses used to secure a helmet system to the head of the wearer are described in U.S. Pat. No. 3,955,570 (Hutter), U.S. Pat. No. 4,280,491(Berg et al.), U.S. Pat. No. 4,901,716 (Stackhouse et al.) and U.S. Pat. No. 5,125,402 (Greenough). Such harnesses are widely used in industry and construction. A ratchet device (e.g., Hutter or Stackhouse et al.) may be used to tighten the head band which, typically, exerts pressure on the head over a small surface area. Pressure sufficient to prevent inadvertent movement of the helmet may be uncomfortable and harnesses may cause disarrangement of the hair and pressure marks on the head and/or forehead.
U.S. Pat. No. 5,381,560 (Halstead) describes a fitting and retention system for headgear including foam pads attached to a plastic (such as expandable polystyrene) liner. The liner is secured to the cranium by means of an adjustable nylon strap which can be positioned to "snugly engage" the occipital protuberance of the head. The intent of the helmet is to protect the head of a bicycle rider in the event of a fall. No mention is made of other applications or uses.
Valves are typically affixed to respiratory protective devices to prevent contaminated air from entering the breathing zone during the inhalation cycle as described in U.S. Pat. No. 5,325,892 (Japuntich et al.). As disclosed in the above-noted Stackhouse et al. patent, unidirectional valves may also be used in clean room devices to prevent contamination of the environment.